Maeda Toshimasu (1543 — 1612), better known as Maeda Keiji, was a Japanese samurai of the Sengoku Period through early Edo Period. Toshimasu was born to the Takigawa Clan of Owari, originally the son of Takigawa Kazumasu. He was adopted by Maeda Toshihisa, the older brother of Maeda Toshiie. Toshimasu served under Oda Nobunaga along with his uncle. Toshimasu was originally intended to inherit Maeda family headship; however, after Oda Nobunaga replaced Toshihisa with Toshiie as Maeda family head, he lost this position. Perhaps because of this loss of inheritance, Toshimasu is well known for not getting along with his uncle.

Toshimasu rode a legendary horse named Matsukaze. The horse was said to be monstrous in size and have immense strength. Because of that, the horse was able to carry Toshimasu's large frame.

While in Kyoto, Toshimasu met and befriended Naoe Kanetsugu, Uesugi Kagekatsu's karō. The two became close friends. Consequently, Toshimasu agreed to join Kanetsugu in the Uesugi clan's invasion of Aizu. During the retreat from the failed invasion, Keiji was given the task of leading the rear guard. Riding his horse Matsukaze into battle and brandishing a two-pronged spear, he made a splendid show of force. Due in part to Toshimasu's actions, the Uesugi forces were able to retreat largely intact.

After this, Toshimasu returned to the capital and devoted himself to arts and literature. Keiji was barred from Toyotomi’s Kyushu campaign for his wild way. When the Tokugawa challenged the Uesugi in 1600, he once again fought with Uesugi’s army. In the battle against the Mogami, he broke through the enemy lines with only eight riders, and shattered their formation. After the Uesugi clan's move to the Yonezawa Domain, Toshimasu remained with them, serving as a retainer.

Keiji's armour can still be seen today at the Miyasaka Museum.